The present invention relates generally to liquid supply and dispensing assemblies, and more particularly to a new and improved liquid supply assembly, such as, for example, at least one liquid supply assembly for supplying hot melt adhesive or other thermoplastic materials toward a liquid dispensing assembly, wherein the at least one liquid supply assembly preferably comprises a plurality of gear pump assemblies which are separate and independent with respect to each other such that any one gear pump assembly can be readily removed from the operatively associated drive gear manifold, wherein further, if any one gear pump assembly should seize or become frozen, it will not itself experience any further damage or adversely affect any of the other gear pump assemblies, and wherein still further, the rotary gear members of each one of the plurality of independent gear pump assemblies are fixedly mounted upon rotary shafts which are disposed in an entirely enclosed arrangement within each one of the gear pump assemblies such that external dynamic shaft seals, which can have a tendency to fail and thereby lead to leakage of the materials being supplied, are effectively eliminated.
In connection with liquid dispensing applicator assemblies, and more particularly, in connection with liquid dispensing applicator assemblies which are being used to dispense hot melt adhesives or other thermoplastic materials, a typical applicator assembly conventionally comprises a supply source of the adhesive or thermoplastic material, means for precisely or accurately metering the adhesive or thermoplastic material through the applicator, and means for pumping the adhesive or thermoplastic material to the metering means of the applicator. In connection with particular applications or procedures, it is usually necessary to accurately or precisely meter the liquids being dispensed so as to ensure that a specific or predetermined volume of the liquid is in fact dispensed within a specific or predetermined period of time. For example, in connection with the dispensing of hot melt adhesive materials, it is often necessary to provide a plurality of individual pumps for providing predetermined volumes of the adhesive material, which may in fact comprise similar or different volume amounts or quantities, to discrete, separate, or respective applicator outlets. The individual pumps conventionally comprise rotary gear pumps which are operatively connected to a drive motor through means of a common rotary drive shaft, and dynamic seals, that is, stationary seals which are operatively disposed around or operatively associated with the rotary drive shaft, are provided for effectively preventing any external or outward leakage of the hot melt adhesive material from the applicator assembly at the interfaces defined between the rotary drive shaft and the rotatably driven gears of the rotary gear pumps. An example of such a conventional or PRIOR ART rotary gear pump hot melt adhesive applicator or dispensing assembly is disclosed, for example, within U.S. Pat. No. 6,422,428 which issued to Allen et al. on Jul. 23, 2002.
More particularly, as disclosed within FIG. 1, which corresponds substantially to FIG. 3 of the aforenoted patent, one of a plurality of gear pump assemblies, as utilized within a hot melt adhesive applicator assembly, is disclosed at 20, and it is seen that each gear pump assembly 20 comprises a conventional sandwiched construction comprising three plates 220,222,224 encompassing or enclosing a pair of gears 230,232. Gear 230 comprises an idler gear, whereas gear 232 comprises a driven gear operatively mounted upon a rotary drive shaft 234. The rotary drive shaft 234 has a hexagonal cross-sectional configuration so as to define the drive connection with the driven gear 232, and it is noted that the drive shaft 234 extends through each gear pump assembly 220. A pair of seals 240, only one of which is shown in FIG. 1, are provided within suitable apertures defined within the end plates 220,224 so as to annularly surround the rotary drive shaft 234 and thereby prevent any leakage of the hot melt adhesive material out from the gear pump assembly 20. A threaded port 244 is provided for receiving a temperature sensor for ensuring that each gear pump 20 has been heated to a predetermined temperature level prior to operation, and a rupture disk assembly 242 is provided for pressure relief under over-pressure conditions. A bore 248 is provided for receiving a pressure transducer which can read output liquid pressure, and when the pressure transducer is not being utilized, a plug assembly 250 is adapted to be disposed within the bore 248.
While a gear pump assembly 20 such as that disclosed within the aforenoted patent is operatively viable, the gear pump assembly 20 of the aforenoted type nevertheless exhibits several operative drawbacks and disadvantages. Firstly, for example, it is noted that in view of the fact that the seals 240 of the gear pump assembly 20 are located upon external surface portions of the end plates 220,224 of the gear pump assembly 20, should the seals 240 experience failure, external leakage of the hot melt adhesive material poses obvious maintenance problems, not to mention the likelihood of the leaking hot melt adhesive material causing fouling of other operative components of the gear pump assembly 20. In addition, it has been noted in the aforenoted patent that the rotary drive shaft 234 extends through each one of the gear pump assemblies 20. Accordingly, if, for example, one of the gear pump assemblies 20 should experience failure or exhibit leakage, and therefore needs to be removed for repair or replacement, the particular gear pump assembly 20 cannot in fact simply be removed from the overall applicator assembly. To the contrary, the rotary drive shaft 234 must firstly be removed so as to subsequently permit the particular gear pump assembly 20 to be removed and separated from the other gear pump assemblies 20 in order to repair or replace the failed or leaking gear pump assembly 20. Upon completion of the repair or replacement of the failed or leaking gear pump assembly 20, the repaired gear pump assembly 20, or the new gear pump assembly 20, can effectively be re-inserted into the bank or array of gear pump assemblies 20 whereupon, still further, the rotary drive shaft 234 can be re-installed in connection with the plurality of rotary gear pump assemblies 20 so as to again be operatively engaged with each one of the plurality of rotary gear pump assemblies 20. Still yet further, if one of the gear pump assemblies 20 should experience failure and effectively become frozen, the failed and frozen gear pump assembly 20 will effectively prevent rotation of the rotary drive shaft 234 whereby the failed or frozen gear pump assembly 20 can experience or undergo further damage, and in turn, cause operative freezing or failure of the other gear pump assemblies 20 which are rotatably engaged with and driven by means of the common rotary drive shaft 234.
Accordingly, a need exists in the art for a new and improved gear pump assembly for use in connection with a liquid dispensing assembly wherein the liquid dispensing assembly comprises at least one gear pump assembly, and preferably a plurality of gear pump assemblies which are mounted upon the liquid dispensing assembly such that all of the gear pump assemblies are independent with respect to each other, wherein the plurality of gear pump assemblies are operatively driven by means of a common rotary drive shaft in such a manner that no external dynamic seals are required, that any particular one of the gear pump assemblies can be readily removed from the array or bank of gear pump assemblies independently of the other gear pump assemblies, and subsequently be re-inserted into the array or bank of gear pump assemblies, or replaced by means of a new gear pump assembly, and wherein still further, as a result of the gear pump assemblies being independent with respect to each other and not being operatively driven by means of a common internally disposed rotary drive shaft, then should a particular one of the gear pump assemblies experience failure, such failed gear pump assembly will not experience additional damage or cause the other gear pump assemblies to experience freezing or failure.
Accordingly, it is an object of the present invention to provide a new and improved gear pump assembly, and a new and improved liquid dispensing assembly having the new and improved gear pump assembly incorporated therein.
Another object of the present invention is to provide a new and improved gear pump assembly, and a new and improved liquid dispensing assembly having the new and improved gear pump assembly incorporated therein, wherein the new and improved gear pump assembly effectively overcomes the various operational drawbacks and disadvantages characteristic of PRIOR ART gear pump and liquid dispensing assemblies.
An additional object of the present invention is to provide a new and improved gear pump assembly, and a new and improved liquid dispensing assembly having the new and improved gear pump assembly incorporated therein, wherein each gear pump assembly is operatively engaged with its own independent drive mechanism through means of an end face portion of the gear pump assembly, as opposed to being operatively engaged with a common drive shaft which passes through the sides of all of the gear pump assemblies, whereby the rotary gear drive mechanism for each gear pump assembly is entirely enclosed or encased internally within each gear pump assembly such that external dynamic seals are effectively eliminated so as to prevent any external leakage, of the liquid being supplied, by each gear pump assembly.
A further object of the present invention is to provide a new and improved gear pump assembly, and a new and improved liquid dispensing assembly having the new and improved gear pump assembly incorporated therein, wherein each gear pump assembly is independently mounted upon a drive gear manifold whereby each gear pump assembly is able to be mounted upon, and dismounted from, the drive gear manifold without operatively affecting the other gear pump assemblies such that if a particular one of the gear pump assemblies needs to be removed, repaired, or replaced, that particular or individual gear pump can in fact be removed, repaired, and replaced without requiring the disassembly of any of the other gear pump assemblies with respect to the drive gear manifold.
A last object of the present invention is to provide a new and improved gear pump assembly, and a new and improved liquid dispensing assembly having the new and improved gear pump assembly incorporated therein, wherein each gear pump assembly is independently mounted upon a drive gear manifold whereby each gear pump assembly is able to be mounted upon, and dismounted from, the drive gear manifold without operatively affecting the other gear pump assemblies such that if a particular one of the gear pump assemblies should experience failure, such failure will not result in any additional damage to the failed gear pump assembly, and in turn, will not cause seizure or failure of the other gear pump assemblies in view of the fact that the gear pump assemblies of the present invention liquid dispensing assembly are not operatively interconnected together by means of a common drive shaft.
The foregoing and other objectives are achieved in accordance with the teachings and principles of the present invention through the provision of a new and improved gear pump assembly, and a new and improved liquid dispensing assembly having the new and improved gear pump assembly incorporated therein, wherein each gear pump assembly comprises a pair of side plates and a central plate which is sandwiched between the pair of side plates. The central plate has a plurality of cut-out regions defined therein for rotatably accommodating a driven gear, a pump drive gear, and a pump idler gear, and the pair of side plates are similarly provided with a plurality of recesses for rotatably accommodating bearing members within which rotary shafts, operatively connected respectively to the driven gear, the pump drive gear, and the pump idler gear, are rotatably disposed. Each individual gear pump assembly is adapted to be independently mounted upon a drive gear manifold within which a pump drive shaft is rotatably mounted. A circumferential portion of the driven gear of each individual gear pump assembly projects outwardly through an end face of each gear pump assembly, and a drive gear, rotatably mounted upon the pump drive shaft disposed within the drive gear manifold, is adapted to be enmeshed with each driven gear of the gear pump assembly. In this manner, all rotatable components of each gear pump assembly are disposed entirely internally within each gear pump assembly whereby external shafting, and the need for external dynamic seals, has effectively been eliminated, and in addition, the independent mounting of each gear pump assembly upon the drive gear manifold permits each gear pump assembly to be individually or separately operated, serviced, maintained, repaired, or replaced without operatively affecting any of the other gear pump assemblies.